1. Field of the Invention
The present invention is a catalytic reactor for promoting a chemical reaction on a fluid passing therethrough. More specifically, the apparatus is a structure for step-wise heating of a fluid passing therethrough such that the fluid obtains or maintains a temperature wherein the desired chemical reaction, in the presence of a catalyst, can occur.
2. Brief Description of the Related Art
Catalytically supported reactions are used in numerous applications, with the automotive converter being one of the more well known. Catalyst characteristics dictate that these reactions occur within a given temperature range with the operational temperature range being chemistry dependent. When a catalyst reaches its operational temperature range it is said to light-off; prior to reaching light-off the catalyst is too cold to support the desired reaction. After light-off the catalyst temperature must be maintained to support the reaction.
Several methods have been employed to raise the temperature of the catalyst to achieve light-off and/or maintain operational temperature. One common method uses the heat energy in the fluid on which the chemical reaction is to occur. This approach, common in automotive converters, imparts the heat in the exhaust gas, resulting from the combustion in the engine, to the catalyst in the downstream catalytic converter.
A second method which is fluid independent employs an auxiliary heat source. The most common auxiliary source being powered by electricity. In this method, the substrate that supports the catalyst is an electrically conducting material that heats up by its electrical resistance when an electric potential is put across the substrate. Auxiliary heating sources are used primarily where the extraction of heat from the fluid is either too slow to effectuate a timely light-off of the catalyst, or the heat of the fluid is below the light-off temperature of the catalyst.
Auxiliary heating sources, as the name implies, are additional systems to the primary system. It is, therefore, critical that these auxiliary heating systems be highly efficient in bringing the catalyst to or maintaining the catalyst at the appropriate operational temperature. The art is well aware of the efficiency of extremely short-channel, metal-substrate catalysts. When these catalysts are bundled, however, the resulting elements have extremely low resistance thus making electrical heating impractical, due to large current requirements for a given electrical potential resulting in excessive power supplies and cables. Currently, spacing is used to solve this problem, but the resulting devices are extremely long. A method of efficient bundling that permits auxiliary electrical resistive heating is required.